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Monday, October 26, 2015

During the Halloween season, we find ourselves surrounded by monsters in movies, stores and decorations. We laugh at the ridiculousness of it all, oblivious to the fact that there are true monsters on our planet today! Mind you, these are not monsters in that they are evil, but they do have many of the same abilities and inclinations of our own mythical werewolves, vampires, zombies and shape-shifters.

Werewolf birds:

A Barau's petrel. Photo by SEOR
available at Wikimedia Commons.

Barau’s petrel is a migrating sea bird that is most active during nights with a full moon. Researchers tied bio-loggers on the birds’ feet to track their activity levels and found that under the full moon, the birds spent nearly 80% of these moonlit nights in flight! It is thought that since these birds migrate longitudinally (parallel with the equator), they can’t use changes in day length as a cue to synchronize their breeding, so they use the phases of the moon instead.

Vampire bats:

Three different bat species feed solely on blood: the common vampire bat, the hairy-legged vampire bat and the white-winged vampire bat. Feeding on blood is not uncommon – The actual term for it is hematophagy, and it is common in insects (think of those pesky mosquitos) and leeches. Although we don’t commonly think of it this way, blood is a body tissue and, like meat, it is rich in protein and calories. The reason it has not become a more popular food source among mammals is probably because it is so watered down (literally) compared to meat, that it can’t provide enough nutrition to sustain a large warm-bodied mammal. This is where our little vampire bat friends come in… small, stealthy, and with specialized saliva that prevents their victims’ blood from clotting, these guys are able to take advantage of this abundant resource, drinking up to half of their body weight in blood every night.

Zombees:

Scientists have recently discovered some strange honey bees: They mindlessly leave their hives in the middle of the night and fly in circles, often towards lights. It turns out that these honey bees are being parasitized by a species of phorid fly called the zombie fly. Female phorid flies lay their eggs inside the abdomens of honey bees, where the eggs hatch into larvae. The larvae feed on the insides of their bee hosts until they are mature enough to leave through the poor bee’s neck (the honey bee is generally dead by this time). Once out, the zombie flies develop into adults so they can breed and start the cycle anew with a new bee host. This phenomenon is still in the early stages of discovery, so if you would like to get involved in this project by watching honey bees in your area, check out ZomBee Watch, a citizen science project to track this zombie infestation.

Shape shifters:

The mimic octopus is a small harmless octopus that lives on the exposed shallow sandy bottoms of river mouths. To avoid its many predators it has developed an amazing strategy: it pretends to be something else, morphing its body into new shapes, like the shape of a deadly lion-fish, a poisonous flatfish, a venomous banded sea-snake, or any number of other animals that live in the area. Not only does the mimic octopus change its shape, it also changes its behavior to match its “costume” to convincingly fool predators. Most cephalopods, which include octopuses, are well-known for their ability to change the color, pattern and texture of their skin to blend in with rocks, coral and plants. Furthermore, octopuses do not have rigid skeletal elements, which allows their bodies great flexibility in the forms they imitate. But this ability to change both physical appearance and behavior to switch back and forth among imitations of multiple species is unique to this astounding shape shifter.

Monday, October 19, 2015

Vampire mythologies have been around for thousands of years, terrifying the young and old alike with stories of predatory bloodsuckers that feed on our life essences. You may not believe in vampires, but they are all around us. In fact, you may have some in the room with you right now! You just don’t notice them because they are not human, or even human-like.

Vampires feed on the blood of their victims in order to sustain their own lives. This phenomenon, called hematophagy, is more common than typically occurs to us at first. Just take mosquitoes and ticks as examples. Once we’ve opened our minds to the idea of bloodthirsty arthropods, we quickly think of many more: bedbugs, sandflies, blackflies, tsetse flies, assassin bugs, lice, mites, and fleas. In fact, nearly 14,000 arthropod species are hematophages. We can expand our thoughts now to worms (like leeches), fish (such as lampreys and candirús), some mammals (vampire bats), and even some birds (vampire finches, oxpeckers, and hood mockingbirds). We’ve been surrounded by vampires our whole lives, we just never sat up to take notice!

Hematophagous animals are not as scary as mythical vampires, in part because they don’t suck their victims dry – they just take a small blood meal to sustain their tiny bodies. Hematophagy is not, in itself, lethal. However, the process of exposing and taking the blood of many individuals transmits many deadly diseases, like malaria, rabies, dengue fever, West Nile virus, bubonic plague, encephalitis, and typhus.

Because blood feeders do not kill their meals, feeding can be even more dangerous for them than for traditional predators. As a result, many hematophagous animals have developed a similar toolkit. Many have mouthparts that are specialized to work as a needle or a razor and biochemicals in their saliva that work as anticoagulants and pain killers. Their primary skill, however, is their stealth: they can sneak up on you, eat their meal, and be home for bed before you even notice the itch.

Although a few species, like assassin bugs and vampire bats, are obligatory hematophages (only eat blood), most hematophages eat other foods as well. Somehow, Dracula is not quite so intimidating when you imagine him drinking his morning fruit juice, like many mosquitoes do.

Why drink blood in the first place? Blood is a body tissue like any other, and it contains a lot of protein and a variety of sugars, fats and minerals, just like meat. However, blood is mostly water, which means that a blood meal contains less protein and calories than the same weight of meat. Because you need to consume so much more to get enough protein and calories out of a meal, large animals and animals that generate their own body heat can't usually rely on blood meals alone. So much for human-like vampires that only live off the blood of their victims.

A deadly vampire spreading malaria. Photo by the CDC available at Wikimedia.

So true vampires are everywhere, but they are small, take small blood meals, don't generally kill their hosts, and often use blood to supplement their other meals. Not so scary any more, are they? ...Although, about 3.2 billion people (about half the world's population) are at risk of contracting the deadly disease, malaria, from these bloodsuckers... so maybe you aren't scared enough. Bwaa-haha!

Monday, October 12, 2015

Man’s Best Friend is a title that has been passed onto our four-legged, drooling counterpart. Dogs have been at man’s side for a number of years showing us his dedication and protection. In the 19th Century, humans started breeding dogs as a hobby. Today, humans have created more than 400 breeds, with less than 200 being recognized by the American Kennel Club, and all can be traced back to the same canid ancestors similar to the gray wolf. As humans selectively bred dogs based on their physical appearances to make a fashion statement, beneath the skin genetic and physiological changes where happening that would have a far harsher consequence to dogs’ health. One such breed is the English Bulldog.

All dog breeds have what are known as breed standards that are set by the Kennel Club or the American Kennel Club. These standards dictate what the breed should look like physically. At first, dogs were bred on a guideline of form follows function. Bulldogs were bred to help butchers control bulls in the slaughter yard. They had long snouts with strong jaws, necks and shoulder muscles while also being tall, allowing them to be quick and agile. However, during the fashion era of dog breeding in the 19th century, breeding became more of a hobby for physical appeal rather than for the dog to have a purpose… which brought us the bulldog we see today.

Head Comparison of a Bulldog (bottom)
and that of a Labrador Retriever (above).
Bulldog image “Camilla, the english bulldog,”
by Trevomeisel at Wikimedia. Labrador
image and edits done by Sarah Johanson.

Over time, the bulldogs’ upper jaws and snouts have been shortened by a significant amount, giving them those mushed short faces. They were bred this way because people thought they looked cute. This shortening is caused by a genetic mutation which causes a developmental defect during bone formation. It’s thought the defect became prevalent due to severe inbreeding. This shortening of the upper jaw has led to there not being enough space in bulldogs’ mouths. Their tongues and palates are often compressed, with the teeth on their lower jaws protruding out in odd directions as their teeth don’t fit, leading to problems with eating and chewing food.

Bulldog nostrils have also been compressed to the point that they can barely breathe. If a human were to breathe like the bulldog, it would be like breathing through a straw. Having a small airway has led the bulldog to become easily overheated and exercise intolerant. To cool down most dogs pant, using water as a tool to take heat away with it as it evaporates. Due to the soft palates not being able to fit in the dogs’ mouths and the narrowing of their throats, panting interferes with breathing. This leads to the production of foam, which blocks the airways even more, sometimes causing suffocation.

Bulldogs are also unable to mate on their own or give birth successfully. Due to their short, stocky bodies, very wide shoulders and narrow pelvises, most males cannot breed with the female on their own. The female either needs to be attached to a breeding stand which gives her body support in order to bear the male’s weight or she needs to be artificially inseminated. Furthermore, a natural birth is almost impossible as the puppies’ heads are too large to fit through the breed’s narrow pelvis to leave the body. This condition, known as dystocia, causes over 80% of bulldog births to be performed via caesarian section. Almost all bulldog births need some kind of human assistance; otherwise they would risk the life of the mother and her unborn puppies.

Diagram of bulldog body shape demonstrating how the “box head” of the breed cannot fit through
the pelvic bone (triangle) during birth due to size and shape. Image created by Sarah Johanson.

These are only some of the physical challenges bulldogs face, not to mention all of the medical problems that could follow. It has been the selective breeding done by breeders and the breed standards set that have turned this dog from the power it once was to the mess that it is today. The bulldog became a fashion statement and although he continues to want to please his human counterpart, his body cannot keep up with his desire.

Monday, October 5, 2015

"Ants biting the underside of leaves as a result of infection
by O. unilateralis. The top panel shows the whole leaf with
the dense surrounding vegetation in the background and the
lower panel shows a close up view of dead ant attached to
a leaf vein. The stroma of the fungus emerges from the back
of the ant's head and the perithecia, from which spores are
produced, grows from one side of this stroma, hence the
species epithet. The photograph has been rotated
to aid visualization." Image and caption by David P. Hughes
and Maj-Britt Pontoppidan at Wikimedia Commons.

The parasitic fungus, Ophiocordyceps unilateralis sensu latu (O. unilateralis, for short), infects the brains of Carpenter ants, turning them into zombies that live and die for the sole purpose of helping the fungus thrive and reproduce. Under the influence of the fungus, zombie Carpenter ants leave their nests at an odd yet specific time, move randomly and convulsively, and climb up the north side of a plant to almost exactly 25 cm, where they bite the leaf vein. Once they bite the leaf, the muscles of their mandibles (mouth parts) deteriorate, causing lockjaw and fixing the ant victim in place while its legs kick and twitch. After a few hours, the movement stops as the fungus kills the ant, continues to grow throughout the victim's head, and then sprouts out of the back of the head. The fungus anchors itself to the plant and releases antimicrobial chemicals to protect itself and grows fruiting bodies from the ant's head to release its spores, spawning the next generation of fungus. O. unilateralis has been known to infect and wipe out entire Carpenter ant colonies, leaving dense aerial graveyards of ant carcasses in its wake.

Today at Accumulating Glitches, I talk about new research that has used genetic techniques to determine how this parasitic fungus takes over the minds of its ant victims. Check it out here.

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Miss Behavior’s real name is Sarah Jane Alger and she is a biologist and student of life. Friend/Follow her on Facebook and/or Google+ (look for this picture) to get updates on The Scorpion and the Frog.